Download Deeper soil salvaging depths produce greater cover of native plants

Research Note
Dec. 2015
#9
Deeper soil salvaging depths produce
greater cover of native plants than
shallow salvage depths on a reclaimed
coal mine site
Research led by: Ellen Macdonald and Simon Landhäusser
The Challenge
The forest understory serves as a key source of plant diversity
and plays an important role in various forest processes.
However, re-establishment of the forest understory community
has proven challenging when using conventional reclamation
techniques because of limited availability of native seed
propagules.
To overcome some of these challenges, direct placement of
forest floor material – where salvaged soils are transferred
directly to a reclamation site – has been encouraged. This
technique preserves native propagules in soils and can improve
forest recovery. However, an important question remains:
what soil salvage depth provides the greatest ecological
benefit?
The Approach
We sought to determine how native forest understory species
responded to direct placement of forest floor material at two
target depths. Material was salvaged from an aspen
dominated forest. Target depths for salvage of suitable
material were 15 cm and 40 cm and the material was directly
transferred to a reclamation site with the same target
placement depths of 15 cm and 40 cm. Vegetation surveys
(percent cover of each species) were completed over the
course of three years following reclamation of the site (i.e.,
2010, 2011, 2012).
The Results
Direct placement of forest floor material helped establish a
diverse plant community including native forest understory
species. The deeper soil salvage depth (40 cm) was better than
the shallow salvage depth (15 cm) at establishing a forest
understory plant community characteristic of the boreal forest.
The benefits of the deeper salvage and placement were
clearest three years after reclamation. At this stage the 40 cm
salvage depth contained forbs, shrubs and trees that were
representative of a range of successional stages of boreal
forests. In contrast, sites with the shallower 15 cm soil depth
Fig. 1 Understory plant communities developing after
direct placement of salvaged soil.
contained more competitive species that were only
representative of early successional stages.
Management Implications
- Direct placement of forest floor material can help native
forest understory species establish on reclaimed sites,
particularly in combination with a developing tree canopy
-
Using deeper salvage depths (i.e., 40 cm vs 15 cm), where
possible, helps less competitive native forest understory
species to establish on the reclaimed site.
-
Salvaging forest floor material at greater depth and then
placing it more shallowly over larger areas could be
effective in reducing costs and increasing restoration
success.
Further Reading
Macdonald, S.E., A.E.K. Snively, J.M. Fair, S.M. Landhäusser.
2015. Early trajectories of forest understory development on
reclamation sites: influence of forest floor placement and a
cover crop. Restoration Ecology 23:698-706.
Acknowledgements
Funding was generously provided by: NSERC; Capital Power;
and the Canadian Oil Sands Network for Research and
Development (CONRAD) through Syncrude Canada Ltd., Suncor
Energy Inc., and Shell Canada.
This summary was prepared by Matthew Pyper – Fuse
Consulting Ltd.
For more info or to get a copy of our publication contact Ellen Macdonald ([email protected]).